Temperature conditioned stuffing box with fluid containment

ABSTRACT

A temperature conditioned stuffing box includes a housing having an outer surface, an inner surface defining a packing-receiving bore, a lower surface for attaching to a wellhead and an upper surface. A flow passage through the housing for passing temperature-conditioned fluid through the housing has an input and an output.

FIELD

A stuffing box for a wellhead that is temperature conditioned.

BACKGROUND

A stuffing box is a packing gland chamber used to hold packing materialcompressed around a moving pump rod to reduce the escape of fluids froma well. Instead, the well fluids are directed to a production line. Incold temperatures, stuffing boxes may begin to leak well fluids, thegrease or oil may become more viscous, and the well head may freeze. Inwarm temperatures, the lubricant is less viscous and therefore moredifficult to control, which may result in the packing becoming brittleand fatigue more rapidly.

SUMMARY

There is provided a temperature conditioned stuffing box, comprising ahousing having an outer surface, an inner surface defining apacking-receiving bore, a lower surface for attaching to a wellhead andan upper surface. A flow passage through the housing for passestemperature-conditioned fluid through the housing, the flow passagehaving an input and an output.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the followingdescription in which reference is made to the appended drawings, thedrawings are for the purpose of illustration only and are not intendedto be in any way limiting, wherein:

FIG. 1 is a side elevation view in section of a temperature conditionedstuffing box with containment.

FIG. 2 is a side elevation view in section of a temperature conditionedstuffing box attached to a wellhead.

FIG. 3 is a side elevation view in section of a temperature conditionedstuffing box without containment.

FIG. 4 is a top plan view of a temperature conditioned stuffing boxshowing the containment cavity and vertical passages for the temperatureconditioned housing.

FIG. 5 is a partially transparent bottom plan view showing a passage ofthe temperature conditioned housing connecting two vertical passages.

FIG. 6 is a perspective view of a flow path.

DETAILED DESCRIPTION

A temperature conditioned stuffing box generally identified by referencenumeral 10, will now be described with reference to FIG. 1 through 6.

Structure and Relationship of Parts:

In cold temperatures, the stuffing boxes 10 tend to leak well fluids.Referring to FIG. 2, it has been found that one of the causes of thisleakage is that, as the packing gland 12 in a stuffing box 10 becomescold, it does not compress around the polish rod 14. In addition, incold temperatures, the lubricant, such as grease or oil, may also become stiff and less effective. Furthermore, most wells in cold weatherwill freeze at the wellhead 16, including the stuffing box 10. By usinga temperature conditioned stuffing box 10 as described herein, thiseffect can be prevented, or at least reduced, resulting in less spillageand torn packing glands 12 in the stuffing box 10. In warm temperatures,the stuffing boxes 10 also risk leaking as the lubricant becomes moredifficult to control, resulting in more brittle packing that fatiguesmore rapidly. In both situations, a more moderate temperature may reducethe risk of leakage.

FIG. 2 shows the temperature conditioned stuffing box housing 18 on atypical wellhead 16, flanged above a flow-tee 22 of the wellhead 16 andthe radigan blowout preventer 24. Below that is the wellhead tubingbonnet 28. Above the stuffing box 10 is a driver 30 that drives thepolish rod 14. While the driver 30 is shown to be a hydraulic cylinder,it will be understood that the stuffing box 10 may be adapted to be usedwith polish rods 14 that rotate or that reciprocate, and that the driver30 may therefore be a drive head that rotates the polish rod 14, or apumping jack the reciprocates the rod vertically.

As the drive head 30 or jack causes fluids to be pumped from the well,the fluids come up the well into the wellhead 16, and exit through theflow-tee 22. The packing glands 12 of the stuffing box 10 seal againstthe polish rod 14 to prevent fluid from flowing up through the stuffingbox 10. The stuffing box 10 is preferably provided with a lantern spring32 to compress the packing 12 as it wears. A plate 36 is bolted over thespring 32 and the packing gland cavity 38 to enclose the packing. Acavity 38 is located at the top of the stuffing box 10 above the plate36 that contains the packing 12 and where the polish rod 14 exits thepacking glands 12. The driver 30 or another plate 40 may be bolted ontop to form a containment chamber 42 with the cavity 44 to contain anyfluids that leak through the packing glands 12. As the chamber 42 fillswith fluid, it may be piped to a holding system 45 through a test cock46.

Referring to FIG. 1 and FIG. 3, the housing 18 of the stuffing box 10 isformed to have a “temperature conditioned housing”, with an input 48 andan output 50 for temperature conditioned fluid to flow through. Examplesof heated fluids that are generally available on a well site includeheated water, steam, hydraulic oil, engine coolant, etc. Examples ofgenerally available cooling fluids include water, such as pumping waterthrough the passages, etc. It will be understood that any suitable fluidmay be used to heat or cool the housing 18. The temperature-conditionedfluid may be used to maintain the packing gland 12 at a constanttemperature or within a preferred temperature range. The housing 18 maybe formed by casting, machining, or a combination of methods. Referringto FIG. 4 and FIG. 5, the passages 52 in the housing are preferably madeby machining, and connect the various passages 52 to create a flow paththat flows around the packing glands 12 (not shown in these figures) inthe body. This may be done by having a series of inputs 48 and outputs50 that connect the passages 52 externally, or preferably, by sealingthe holes at the surface of the housing 18 while leaving the adjacentchannels 52 connected inside the housing 18. The channels 52 may beformed vertically as well as horizontally to achieve a higher coverage.FIG. 5 shows a series of horizontal and vertical passages 52 that passaround the stuffing box 10. Since the passages 52 are preferably made bymachining from the surface, the outside of these passages 52 are filledor plugged to prevent fluid from escaping. An example of a completedflow path between input 48 and output 50 made up of various passages 52is shown in FIG. 6. It will be understood that other flow paths may bemade using the principles discussed herein, which may or may not involve90 degree corners as shown.

There are different ways of controlling the temperature of the stuffingbox 10. Since the stuffing box 10 is able to operate in a range oftemperatures, it is not always necessary to maintain a specifictemperature, such as by using a thermostat, although it is possible todo so. Two main ways of controlling the temperature of stuffing box 10are to control the temperature of the fluid entering housing 18, and tocontrol the flow rate of the fluid through housing 18. For example,heated coolant from an engine, or heated hydraulic oil are readilyavailable sources of heated fluid. However, it is generally easier toprovide a flow control that restricts the amount of fluid that entersthe housing than to control the temperature of the coolant or oil.

In this patent document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word are included,but items not specifically mentioned are not excluded. A reference to anelement by the indefinite article “a” does not exclude the possibilitythat more than one of the element is present, unless the context clearlyrequires that there be one and only one of the elements.

The following claims are to understood to include what is specificallyillustrated and described above, what is conceptually equivalent, andwhat can be obviously substituted. Those skilled in the art willappreciate that various adaptations and modifications of the describedembodiments can be configured without departing from the scope of theclaims. The illustrated embodiments have been set forth only as examplesand should not be taken as limiting the invention. It is to beunderstood that, within the scope of the following claims, the inventionmay be practiced other than as specifically illustrated and described.

1. A temperature conditioned stuffing box, comprising: a housing havingan outer surface, an inner surface defining a packing-receiving bore, alower surface for attaching to a wellhead and an upper surface; and aflow passage through the housing for passing temperature-conditionedfluid through the housing, the flow passage having an input and anoutput.
 2. The temperature conditioned stuffing box of claim 1, whereinthe housing has a containment chamber positioned toward the uppersurface of the housing relative to the packing-receiving bore.
 3. Thetemperature conditioned stuffing box of claim 2, wherein the containmentchamber is formed from a cavity in the upper surface, and a driverattached to the upper surface.
 4. The temperature conditioned stuffingbox of claim 1, wherein the housing is a unitary piece of material, andthe flow passage is formed from a series of connected machined passages.